Noise Reduction by Applying Modulation Principles
作者:
Donald Ewald,
Armin Pavlovic,
John G. Bollinger,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1971)
卷期:
Volume 49,
issue 5A
页码: 1381-1385
ISSN:0001-4966
年代: 1971
DOI:10.1121/1.1912513
出版商: Acoustical Society of America
数据来源: AIP
摘要:
This paper presents techniques for determining nonperiodic spacing of events for the purpose of reshaping noise‐frequency spectra. The object of the application is to provide reduced noise levels and the redistribution of the frequencies at which there is noise energy so as to generate fewer perceptible sounds. Three analytical techniques for predicting the noise spectrum resulting from nonuniform spacing are presented. Emphasis is focused on a semigraphical design technique using Bessel functions, which has proven to be of great value in the actual selection of modulated event spacing. Fourier analysis of an impulse approximation and a sinusoidal wave approximation are two other alternative techniques presented. The techniques outlined are applied to the problem of reshaping the noise spectrum of a 22‐blade fan in a 5‐hp induction motor. A comparison of predicted results provides an evaluation of the alternative approaches.
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